Today, there are numerous situations in which confirming the type of vehicle passing over a spot on the road is important. While visual inspections can provide a good deal of information, they do not readily report the magnetic signature of a vehicle, which can reveal additional details about the vehicle contents. Methods are needed for determining that magnetic signature in a cost effective and reliable manner.
The situation has some significant hurdles. Running wires to sensors embedded in roadways turns out to be difficult, expensive, and often unreliable in the rugged environment of a roadway with multiple ton vehicles rolling over everything on a frequent basis. What is needed is a way to use a wireless vehicular sensor node to report something approximating the raw vehicular sensor waveform via wireless communications.
Wireless vehicular sensor networks often use repeaters and/or some of the vehicular sensor nodes to wirelessly convey wireless messages from distant sensor nodes to where they are collected, which will be referred to herein as intermediate nodes. These intermediate nodes are usually essentially invisible to the network, but add a significant delay to the time from the sending of the messages, and their reception at the collection node. Additionally, a wireless vehicular sensor network may not provide a ready mechanism to time synchronizing these messages, making it difficult form an accurate picture of the magnetic signatures of the sensor state of these systems taken as a whole. What is needed are methods and mechanisms supporting the time synchronization of these reports which allows a view of the system state at a given moment to be assembled.
There are additional problems which cannot be currently addressed. In many areas, it would be very useful to know the ambient conditions at the wireless vehicular sensor nodes. For example, a change from 100 degrees Fahrenheit to 50 degrees or from twenty percent to 90 percent relative humidity can indicate that the transmission properties of the air have changed, potentially altering the interpretation of the received waveforms being reported. Today, there are no wireless vehicular sensor nodes capable of reporting such ambient conditions.
In places where snow and ice can occur, it is often important to know if and where ice can form, and for how long. In places where intense rain may occur, it is often important to know how much water is standing on or near a roadway. What is needed are cost effective methods and mechanisms for the wireless vehicular sensor node to provide such ambient condition reports and for a traffic or public service portal to use those reports to create road condition reports, which can collectively improve the public welfare of their community by providing a network of remote sensors that can provide a real time maps to snow and ice conditions, standing water, and fog estimates.